<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8" />
  <title></title>
  <link rel="stylesheet" href="index.css" />
</head>

<body>
  <h1>窗口标题</h1>
  <button id="btn">点击打开新窗口</button>
</body>
<script src="./teml.js"></script>
</html>